Clinical implications of genetic defects in G proteins: oncogenic mutations in G alpha s as the molecular basis for the McCune-Albright syndrome

Malignant transformation of craniofacial fibrous dysplasia: A clinicopathological, immunohistochemical and molecular analysis of 15 cases in one single institution

OBJECTIVE

Malignant transformation of craniofacial fibrous dysplasia (FD) is not common and its clinicopathological as well as molecular characteristics remain largely unknown with limited literature reports.

STUDY DESIGN

Patients diagnosed with FD including McCune-Albright syndrome (MAS), polyostotic fibrous dysplasia (PFD), and monostotic fibrous dysplasia (MFD), accompanied by malignant transformation at our institution over the past 18 years (2005-2023) were retrospectively screened and analyzed to investigate the epidemiology and clinicopathological features of these tumors.

RESULTS

Three hundred and five patients were diagnosed as FD in our hospital from 2005 to 2023, with 176 females (57.7 %) and 129 males (42.3 %). The average age at diagnosis was 28.35 years, ranging from 7 to 70 years. A total number of 15 (4. 9 %) cases of FD with malignant transformation were selected. Among these 15 patients, the age of the initial diagnosis of FD ranged from 6 to 54 years (mean age 28.87 ± 16.77), and the ages when malignant transformation occurred ranged from 18 to 57 years (mean age 38.53 ± 13.05). Among 15 patients, 12 patients were female (80 %) and 3 were male (20 %). Fifteen cases included MSA in 2 patients, PFD in 4 patients, and MFD in 9 patients. Of the anatomical sites in craniofacial bones, the most common site of the lesion was the maxilla, followed by the mandible. Malignant neoplasm arising in FD were osteosarcoma (12/15), chondrosarcoma (1/15) and high-grade sarcoma of uncertain differentiation (2/15). The 3- and 5-year overall survival rate was 33.3 % (5/15) and 20 % (3/15) respectively. In secondary osteosarcoma from FD, MDM2 and CDK4 positivity were 33.3 % and 41.7 % respectively, and only one case was MDM2-amplified and CDK4-amplified.

CONCLUSION

Malignant transformation in fibrous dysplasia was an exceedingly rare event and with a female predominance. The overall survival rate was poor. Osteosarcoma was the most common malignant neoplasm arising in FD. MDM2 and CDK4 expression may aid in the diagnosis of secondary osteosarcoma in FD.

A Rare Skeletal Disorder, Fibrous Dysplasia: A Review of Its Pathogenesis and Therapeutic Prospects

Fibrous dysplasia (FD) is a rare, non-hereditary skeletal disorder characterized by its chronic course of non-neoplastic fibrous tissue buildup in place of healthy bone. A myriad of factors have been associated with its onset and progression. Perturbation of cell-cell signaling networks and response outputs leading to disrupted building blocks, incoherent multi-level organization, and loss of rigid structural motifs in mineralized tissues are factors that have been identified to participate in FD induction. In more recent years, novel insights into the unique biology of FD are transforming our understandings of its pathology, natural discourse of the disease, and treatment prospects. Herein, we built upon existing knowledge with recent findings to review clinical, etiologic, and histological features of FD and discussed known and potential mechanisms underlying FD manifestations. Subsequently, we ended on a note of optimism by highlighting emerging therapeutic approaches aimed at either halting or ameliorating disease progression.

Postoperative thyroid crisis in an 11-year old male with McCune-Albright syndrome and atypical triiodothyronine hyperthyroidism: A case report

RATIONALE

McCune-Albright syndrome (MAS) is a rare heterogeneous clinical disease caused by sporadic, somatic, and postzygotic mutations. Thyroid crisis is even rare in patients with MAS, and we report the clinical outcomes of the first case of a MAS patient with atypical triiodothyronine (T3) hyperthyroidism who developed thyroid crisis after orthopedic surgery.

PATIENT CONCERNS

The patient with MAS and atypical T3 hyperthyroidism was an 11-year-old man who had undergone surgery for a right femur fracture and shepherd bending deformity. His main symptoms were dizziness, nausea, and vomiting with elevated body temperature because of developed thyroid crisis. Thyroid function tests showed high T3 and remarkably high free T3 levels, and remarkably increased thyrotropin level, but unchanged thyroxine and free thyroxine levels.

DIAGNOSIS

The patient was diagnosed with postoperative thyroid crisis following surgery for a right femur fracture, shepherd bending deformity, and MAS with atypical T3 hyperthyroidism.

INTERVENTIONS

Propranolol was intravenously administered. The therapy included intravenous hydrocortisone, a saturated solution of potassium iodine and propylthiouracil, and continuous physical cooling.

OUTCOMES

The patient was discharged after achieving a stable condition with normal thyroid and liver function after surgery because of active anti-thyroid crisis treatment.

LESSONS

The operation of such patients should focus on the pre-operative heart rate, platelet level, and thyroid hormone levels. Abnormal values should be adjusted to the normal range, and such patients should achieve complete hemostasis and transfuse with blood following surgery anemia.

The Molecular Biology of Phosphodiesterase 4 Enzymes as Pharmacological Targets: An Interplay of Isoforms, Conformational States, and Inhibitors

The phosphodiesterase 4 (PDE4) enzyme family plays a pivotal role in regulating levels of the second messenger cAMP. Consequently, PDE4 inhibitors have been investigated as a therapeutic strategy to enhance cAMP signaling in a broad range of diseases, including several types of cancers, as well as in various neurologic, dermatological, and inflammatory diseases. Despite their widespread therapeutic potential, the progression of PDE4 inhibitors into the clinic has been hampered because of their related relatively small therapeutic window, which increases the chance of producing adverse side effects. Interestingly, the PDE4 enzyme family consists of several subtypes and isoforms that can be modified post-translationally or can engage in specific protein-protein interactions to yield a variety of conformational states. Inhibition of specific PDE4 subtypes, isoforms, or conformational states may lead to more precise effects and hence improve the safety profile of PDE4 inhibition. In this review, we provide an overview of the variety of PDE4 isoforms and how their activity and inhibition is influenced by post-translational modifications and interactions with partner proteins. Furthermore, we describe the importance of screening potential PDE4 inhibitors in view of different PDE4 subtypes, isoforms, and conformational states rather than testing compounds directed toward a specific PDE4 catalytic domain. Lastly, potential mechanisms underlying PDE4-mediated adverse effects are outlined. In this review, we illustrate that PDE4 inhibitors retain their therapeutic potential in myriad diseases, but target identification should be more precise to establish selective inhibition of disease-affected PDE4 isoforms while avoiding isoforms involved in adverse effects. SIGNIFICANCE STATEMENT: Although the PDE4 enzyme family is a therapeutic target in an extensive range of disorders, clinical use of PDE4 inhibitors has been hindered because of the adverse side effects. This review elaborately shows that safer and more effective PDE4 targeting is possible by characterizing 1) which PDE4 subtypes and isoforms exist, 2) how PDE4 isoforms can adopt specific conformations upon post-translational modifications and protein-protein interactions, and 3) which PDE4 inhibitors can selectively bind specific PDE4 subtypes, isoforms, and/or conformations.

Fibrous dysplasia of the sinonasal tract and adjacent skull base

PURPOSE OF REVIEW

Fibrous dysplasia is a rare condition characterized by replacement of normal bone by fibro-osseous connective tissue exhibiting varying degrees of osseous metaplasia, which can affect the craniofacial complex. This article reviews the recent literature with the intent to highlight the innovative information that has contributed to elucidate the pathophysiology, diagnostic criteria, and treatment principles of the disease.

RECENT FINDINGS

A mutation in the GNAS1 gene on chromosome 20 has been identified as the molecular hallmark of fibrous dysplasia. This finding is not present in ossifying fibroma, which has been traditionally included in differential diagnosis. The concept that asymptomatic patients do not require surgical treatment has been reinforced by a meta-analysis specifically addressing the issue of optic nerve decompression.

SUMMARY

A diagnosis of fibrous dysplasia can be achieved by combined assessment of clinical, radiologic, and pathologic findings. There is general agreement that, when the disease is not associated with symptoms, partial or radical resection is not indicated, but patients do require periodic radiologic evaluations. There is, however, an absolute need for prospective studies to identify factors predicting the possible late growth of the disease and to investigate the efficacy and side-effects of pharmacological treatment with biphosphonates.

Polyostotic fibrous dysplasia with gigantism and huge pelvic tumor: a rare case of McCune-Albright syndrome

We report a rare case of polyostotic fibrous dysplasia on endocrine hyperfunction with elevated human growth hormone and normal serum level of prolactin. There were some differential points of gender, gigantism, endocrine function, and GNAS gene from McCune-Albright syndrome. Malignant transformation was suspected in the pelvic tumor from imaging because rapid growth of the tumor by imaging was observed; however, no malignant change occurred in this case.

The genetics of pituitary adenomas

Pituitary adenomas are one of the most frequent intracranial tumors with a prevalence of clinically-apparent tumors close to 1:1000 of the general population. They are clinically significant because of hormone overproduction and/or tumor mass effects in addition to the need for neurosurgery, medical therapies and radiotherapy. The majority of pituitary adenomas have a sporadic origin with recognized genetic mutations seldom being found; somatotropinomas are an exception, presenting frequent somatic GNAS mutations. In this and other phenotypes, tumorigenesis could possibly be explained by altered function of genes implicated in cell cycle regulation, growth factors or their receptors, cell-signaling pathways, specific hormonal factors or other molecules with still unclear mechanisms of action. Genetic changes, such as allelic loss or gene amplification, and epigenetic changes, usually by promoter methylation, have been implicated in abnormal gene expression, but alternative mechanisms may be present. Familial cases of pituitary adenomas represent 5% of all pituitary tumors. MEN1 mutations cause multiple endocrine neoplasia type 1 (MEN1), while the Carney complex (CNC) is characterized by mutations in the protein kinase A regulatory subunit-1alpha (PRKAR1A) gene or changes in a locus at 2p16. Recently, a MEN1-like condition, MEN4, was found to be related to mutations in the CDKN1B gene. The clinical entity of familial isolated pituitary adenomas (FIPA) is characterized by genetic defects in the aryl hydrocarbon receptor interacting protein (AIP) gene in about 15% of all kindreds and 50% of homogenous somatotropinoma families. Identification of familial cases of pituitary adenomas is important as these tumors may be more aggressive than their sporadic counterparts.

Developmental etiology for neuroanatomical and cognitive deficits in mice overexpressing Galphas, a G-protein subunit genetically linked to schizophrenia

Schizophrenia is a widespread psychiatric disorder, affecting 1% of people. Despite this high prevalence, schizophrenia is not well treated because of its enigmatic developmental origin. We explore here the developmental etiology of endophenotypes associated with schizophrenia using a regulated transgenic approach in mice. Recently, a polymorphism that increases mRNA levels of the G-protein subunit Galphas was genetically linked to schizophrenia. Here we show that regulated overexpression of Galphas mRNA in forebrain neurons of mice is sufficient to cause a number of schizophrenia-related phenotypes, as measured in adult mice, including sensorimotor gating deficits (prepulse inhibition of acoustic startle, PPI) that are reversed by haloperidol or the phosphodiesterase inhibitor rolipram, psychomotor agitation (hyperlocomotion), hippocampus-dependent learning and memory retrieval impairments (hidden water maze, contextual fear conditioning), and enlarged ventricles. Interestingly, overexpression of Galphas during development plays a significant role in some (PPI, spatial learning and memory and neuroanatomical deficits) but not all of these adulthood phenotypes. Pharmacological and biochemical studies suggest the Galphas-induced behavioral deficits correlate with compensatory decreases in hippocampal and cortical cyclic AMP (cAMP) levels. These decreases in cAMP may lead to reduced activation of the guanine exchange factor Epac (also known as RapGEF 3/4) as stimulation of Epac with the select agonist 8-pCPT-2'-O-Me-cAMP increases PPI and improves memory in C57BL/6J mice. Thus, we suggest that the developmental impact of a given biochemical insult, such as increased Galphas expression, is phenotype specific and that Epac may prove to be a novel therapeutic target for the treatment of both developmentally regulated and non-developmentally regulated symptoms associated with schizophrenia.

Clinical, microscopic and imaging findings associated to McCune-Albright syndrome: report of two cases

McCune-Albright syndrome is characterized by the triad café-au-lait cutaneous spots, polyostotic fibrous dysplasia and endocrinopathies. This article presents two cases of McCune-Albright syndrome in a middle-aged woman and a young girl. Both patients presented café-au-lait spots on the face and other parts of the body and expansion of the mandible with radiopaque-radiolucent areas with ground-glass radiographic appearance, and were diagnosed as having fibrous dysplasia and endocrine disorders. The patient of Case 1 had fibrous dysplasia on the upper and lower limbs, thorax, face and cranium, early puberty, hyperglycemia, hyperthyroidism and high serum alkaline phosphatase levels. The patient of Case 2 presented lesions on the upper limbs and evident endocrine disorders. In both cases presented in this article, the initial exam was made because of the mandibular lesion. However, a diagnosis of fibrous dysplasia must lead to investigation of the involvement of other bones, characterizing polyostotic fibrous dysplasia, which is manifested in a number of diseases. An accurate differential diagnosis is mandatory to determine the best treatment approach for each case.

Restoration of ovulation after unilateral ovariectomy in a woman with McCune-Albright syndrome: a case report

INTRODUCTION

McCune-Albright syndrome (MAS) is characterized by peripheral precocious puberty, café-au-lait spots, and polyostotic fibrous dysplasia. This syndrome is due to a post-zygotic mutation of the GNAS1 gene with mosaic distribution and unilateral predominance. Clinical manifestations depend on the tissues carrying the mutation. We describe the ovarian function before and after unilateral ovariectomy in a woman with MAS and bilateral distribution of the GNAS1 gene mutation.

CASE REPORT

A 33-year-old patient, previously diagnosed as having MAS, presented irregular menstrual cycles (30-180 days) and monophasic temperature curves. Transvaginal ultrasound and blood tests were repeated at 3-day intervals over 3 months. Findings included a persistent quiescent left ovary, a persistent polycystic right ovary, constantly high estradiol-17beta (E2) levels, and very low FSH and LH levels. She also presented severe persistent pelvic pain. Because of unilateral ovarian activity, a unilateral right ovariectomy was performed as well as biopsy of the remaining left ovary. A GNAS1 gene mutation was identified in both ovaries. A regular monthly menstrual cycle was immediately restored. On day 3 of the menstrual cycle, E2 level was 30 pg/ml, FSH level was 7.5 mIU/ml, and LH level was 6.4 mIU/ml. On day 17, pelvic ultrasound showed one follicle of 25 mm in the left ovary. On day 21, the progesterone level was 13.1 ng/ml.

DISCUSSION

This is the first report of ovulation being restored following unilateral ovariectomy in an adult patient suffering from severe MAS with GNAS1 gene mutation identified in both ovaries.

Studies of the regulation and function of the Gs alpha gene Gnas using gene targeting technology

The heterotrimeric G protein alpha-subunit G(s)alpha is ubiquitously expressed and mediates receptor-stimulated intracellular cAMP generation. Its gene Gnas is a complex imprinted gene which uses alternative promoters and first exons to generate other gene products, including the G(s)alpha isoform XL alpha s and the chromogranin-like protein NESP55, which are specifically expressed from the paternal and maternal alleles, respectively. G(s)alpha itself is imprinted in a tissue-specific manner, being biallelically expressed in most tissues but paternally silenced in a few tissues. Gene targeting of specific Gnas transcripts demonstrates that heterozygous mutation of G(s)alpha on the maternal (but not the paternal) allele leads to early lethality, perinatal subcutaneous edema, severe obesity, and multihormone resistance, while the paternal mutation leads to only mild obesity and insulin resistance. These parent-of-origin differences are the consequence of tissue-specific G(s)alpha imprinting. XL alpha s deficiency leads to a perinatal suckling defect and a lean phenotype with increased insulin sensitivity. The opposite metabolic effects of G(s)alpha and XL alpha s deficiency are associated with decreased and increased sympathetic nervous system activity, respectively. NESP55 deficiency has no metabolic consequences. Other gene targeting experiments have shown Gnas to have 2 independent imprinting domains controlled by 2 different imprinting control regions. Tissue-specific G(s)alpha knockout models have identified important roles for G(s)alpha signaling pathways in skeletal development, renal function, and glucose and lipid metabolism. Our present knowledge gleaned from various Gnas gene targeting models are discussed in relation to the pathogenesis of human disorders with mutation or abnormal imprinting of the human orthologue GNAS.

Pathologic fracture of the femoral neck in a female soccer player

We report a case of a healthy, young, female soccer player who developed progressive pain in her right hip. A bone cystic lesion was found in the right femoral neck and proximal femur. The lesion was considered a benign bone cyst and the patient was treated with injections of autologous bone marrow and grafting into the femoral neck. However, the cystic lesion did not heal. Subsequently, the patient fell and developed a fracture of the femoral neck that required internal fixation. The bone biopsy showed characteristic histologic features of fibrous dysplasia. A bone scan showed other areas of suspected dysplasia. Pamidronate therapy was given, and a reduction of the increased uptake was seen on bone scans. Fibrous dysplasia must be considered in the differential diagnosis of any cystic bone lesion.

Genetic diagnosis of multiple affected tissues in a patient with McCune-Albright syndrome

McCune-Albright syndrome (MAS) is a sporadic disorder characterized by the classic triad of polyostotic fibrous dysplasia, café-au-lait' skin pigmentation, and hyperfunctional endocrinopathy. It is caused by embryonic somatic mutations leading to the substitution of His or Cys for Arg at amino acid 201 of the alpha-subunit of the signal transduction protein Gs (Gsalpha). A 32-year-old man was diagnosed as McCune-Albright syndrome with the following findings: polyostotic fibrous dysplasia, café-au-lait' spots and acromegaly. An ultrasonic examination showed that he had left-pleural effusion, which disappeared after almost a year without special treatment. Genomic DNA was isolated from the peripheral blood, bone tissue, skin lesion and pleura samples of the patient. Then PCR and direct sequencing were performed. An activating mutation of the Gsalpha gene (Arg201Cys) was found in the genomic DNA isolated from the peripheral blood and the bone tissue, but not in genomic DNA isolated from the skin and pleura samples.

A case of McCune-Albright syndrome with associated multiple endocrinopathies

McCune-Albright syndrome (MAS) is a rare disorder that develops from an activating mutation in the Gs gene. It is characterized by an association with Polyostotic fibrous dysplasia, and precocious puberty, Caf-au-lait pigmentation, and other endocrinopathies that result from the hyperactivity of a variety of endocrine glands. Recently we encountered a patient with MAS with fibrous dysplasia, skin pigmentation, acromegaly, hyperprolactinemia and a thyroid nodule. A 23-year-old male presented for an evaluation of a change in his facial structures. Fibrous dysplasia was diagnosed by a bone biopsy and radiographic studies. The GH level increased paradoxically after an oral glucose load. The plasma prolactin, IGF-1 and alkaline phosphatase were high. Thyroid ultrasonography revealed multiple nodules. The brain MRI demonstrated a mass in the left pituitary gland. Genetic analysis identified a change from Arg (CGT) at codon 201 to Cys (TGT).

Runx2 regulates the expression of GNAS on SaOs-2 cells

Runx2 is a key regulator of osteoblast-specific gene expression and controls the expression of multiple target genes during osteoblast differentiation. Although some transcriptional targets for Runx2 are known, it is believed that the osteogenic action of Runx2 is mediated by additional target genes, and increasing studies are performed in order to identify such Runx2-responsive genes. To identify genes following the inhibition of Runx2 in osteoblastic cell line, SaOs-2 was stably transfected with a dominant negative mutant of Runx2 (Deltacbfa1) under the control of a strong promoter. Comparison of gene expression patterns by differential display on selected SaOs-2 clones allowed us to observe that GNAS mRNA which encodes for the Gsalpha protein is overexpressed (5 to 8 fold) in cells presenting high levels of Deltacbfa1. This overexpression was also observed at the protein level and seemed to be reflected by an increased basal cAMP level. Gel shift experiments performed in this study indicate that Runx2 is able to bind to the promoter of GNAS, suggesting a direct regulation at the transcriptional level. Well-described GNAS mutations like fibrous dysplasia or Albright hereditary osteodystrophy are linked to abnormality in osteoblast function, and numerous evidences showed that Gsalpha coupled adrenergic receptors increase the expression of osteotrophic factors and regulate bone mass. Regulation of Gsalpha protein by Runx2 seems to be of particular interest considering the increasing evidences on bone metabolism regulation by G proteins.

Stimulatory G protein directly regulates hypertrophic differentiation of growth plate cartilage in vivo

Stimulatory heterotrimeric G protein (Gs) transduces signals from various cell-surface receptors to adenylyl cyclases, which generate cAMP. The alpha subunit of Gs (Gsalpha) is encoded by GNAS (Gnas in mice), and heterozygous Gsalpha inactivating mutations lead to Albright hereditary osteodystrophy. The in vivo role of Gsalpha in skeletogenesis is largely unknown, because of early embryonic lethality of mice with disruption of Gnas exon 2 (Gnas(E2-/E2-)) and the absence of easily detectable phenotypes in growth plate chondrocytes of heterozygous mutant mice (Gnas(+/E2-)). We generated chimeric mice containing wild-type cells and either Gnas(E2-/E2-) or Gnas(+/E2-) cells. Gnas(E2-/E2-) chondrocytes phenocopied PTH/PTHrP receptor (PPR)(-/-) cells by prematurely undergoing hypertrophy. Introduction of a transgene expressing Gsalpha, one of several gene products that include Gnas exon 2, into Gnas(E2-/E2-) cells prevented premature hypertrophy. Gsalpha mRNA expression detected by real-time RT-PCR analysis was reduced to approximately half that of the wild-type in both paternal and maternal Gnas(+/E2-) growth plate chondrocytes, indicating biallelic expression of Gsalpha in these cells. Hypertrophy of Gnas(+/E2-) chondrocytes was modestly but significantly premature in chimeric growth plates of mice containing wild-type and Gnas(+/E2-) cells. These data suggest that Gsalpha is the primary mediator of the actions of PPR in growth plate chondrocytes and that there is haploinsufficiency of Gsalpha signaling in Gnas(+/E2-) chondrocytes.

The rare phakomatoses

This article outlines the clinical, central nervous system, and neuropathologic features,pathogenesis, genetics, molecular biology, and neuroimaging characteristics of the rare vascular phakomatoses, melanophakomatoses, and organoid phakomatoses.

Aromatase Inhibitors in Precocious Puberty

Aromatase inhibitors have been used in the treatment of selective forms of precocious puberty since the mid-1980s. The primary aim of therapy is attenuation of the effects of estrogen on growth, skeletal maturation, and secondary sexual development. The first-generation agent, testolactone, has been demonstrated to be tolerable and effective in the treatment of familial male precocious puberty, while mixed results with testolactone have been achieved in girls with McCune-Albright syndrome. A favorable outcome with the use of testolactone in conjunction with conventional therapy in children with congenital adrenal hyperplasia has also been suggested. Although a few anecdotal reports of the use of newer generation aromatase inhibitors in precocious puberty exist, the extreme rarity of the relevant disorders remains a limiting factor in clinical investigation. In this review, the pathophysiology, presentation, and treatment of precocious puberty are described. Particular attention is devoted to the specific disorders in which aromatase inhibitors have been utilized, which are forms of peripheral (gonadotropin-independent) precocious puberty. The impact of untreated precocious puberty on growth and adult stature is discussed, and the actions of estrogen in the human skeleton are summarized. Finally, a detailed description of the existing literature pertaining to aromatase inhibitors in the pediatric population is provided. Emerging potential new indications are discussed. In conclusion, aromatase inhibitors, particularly testolactone, have a proven track record in the treatment of a few forms of precocious puberty. Continued exploration with new generation aromatase inhibitors in these disorders is ongoing. The wider application of aromatase inhibitors for the purposes of delaying skeletal maturation and increasing adult height in several conditions leading to short stature is currently a subject of intense investigation.

Dental characteristics of fibrous dysplasia and McCune-Albright syndrome

OBJECTIVE

Fibrous dysplasia (FD) is a skeletal disorder often associated with McCune-Albright syndrome, a rare multisystem disorder caused by GNAS1 gene mutation. FD frequently affects the craniofacial bones, including the maxilla and the mandible; nevertheless, its effects on dental tissues and the implications for dental care remain unclear. The aim of this study was to characterize the dental features associated with FD and the reaction of affected bones to routine dental therapy. Study design Thirty-two patients with FD underwent dental evaluation and endocrine testing as part of the diagnosis of FD/McCune-Albright syndrome. Any dental anomalies were recorded, and the associations between endocrinopathies and dental anomalies were analyzed statistically by means of the paired t test.

RESULTS

Eighty-four percent had FD in the maxilla and/or mandible; endocrine dysfunction; and/or renal phosphate wasting. The caries index scores were 2.9 (ages 4-17 years) and 9.6 (ages 18-50 years). Malocclusion (81%) and other prevalent dental anomalies (41%) included tooth rotation, oligodontia, and taurodontism. The expansion of the maxilla or mandible by FD did not distort the dental arch curvature, and routine dental therapies such as extractions, restorations, and orthodontic treatment did not exacerbate FD lesions.

CONCLUSION

Maxillomandibular FD was associated with higher rates of caries and malocclusion than were present in healthy patients. Furthermore, patients with FD did not require special dental management and were able to undergo routine dental care without an exacerbation of FD lesions.

Paget's disease and fibrous dysplasia

Paget's disease and fibrous dysplasia are benign disorders that can involve the temporal bone and skull base. They commonly lead to otolaryngologic symptoms such as impingement of cranial nerves or the orbit or blockage of the external auditory canal or paranasal sinuses, although they can often be a challenge to diagnose because of their insidious presentation. Their benign nature and common presentation within the difficult-to-access confines of the skull base should lead the clinician to exercise caution in their treatment, reserving surgical intervention for either diagnosis or the relief of symptoms. As a better understanding of the etiology of these conditions develops and new pharmacotherapeutic agents are tested, it is likely that physicians will be able to turn to medical rather than surgical techniques to treat these disorders.

Therapeutic potential of GnRH antagonists in the treatment of precocious puberty

Pituitary-gonadal axis activation depends upon pulsatile hypothalamic gonadotropin-releasing hormone (GnRH) secretion. This phenomenon has led to clinical use of GnRH agonists in the treatment of central precocious puberty. GnRH analogues contain substitutions of the native decapeptide. Depending upon the substitutions, the analogues have GnRH agonistic or antagonistic properties. The pharmacokinetics of GnRH agonists, the established treatment of precocious puberty, includes an initial 'flare-up' of the pituitary-gonadal axis, followed by a reduced luteinising hormone secretion by desensitisation of pituitary GnRH receptors. Antagonistic GnRH analogues act by competitive binding to the pituitary GnRH receptors, thereby preventing the action of endogenous GnRH - theoretically offering a more direct and dose-dependent treatment alternative. The antagonist available today in Germany is a concomitant in assisted reproduction with only 1 - 3 days duration. However, long-acting depot preparations of other GnRH antagonists are in primate-testing phase. Our animal tests indicate strong potential for the development and testing of long-acting depot preparations of GnRH antagonists in treating precocious puberty.

McCune-Albright syndrome: a case report and review of the literature

Nasal obstruction is one of the most common symptoms pediatric patients present to their physicians with. Usually this symptom is caused by allergic rhinitis or an upper respiratory infection, however, many conditions present with nasal obstruction. We present a 14-year-old patient with a rare cause of nasal obstruction, turbinate enlargement due to fibrous dysplasia, as diagnosed by CT scan and histopathologic analysis. Additionally, clinical history revealed precocious puberty, and a dermatologic exam revealed a café au lait macule, consistent with the McCune-Albright syndrome. This case illustrates the need to formulate a broad differential diagnosis and also consider the overall patient, not just the nasal cavity. The clinical presentation, diagnostic evaluation, long-term management plan and relevant literature are discussed.

A novel, complex heterozygous mutation within Gsalpha gene in patient with McCune-Albright syndrome

McCune-Albright syndrome (MAS) is caused by embryonic somatic mutations leading to the substitution of His or Cys for Arg at amino acid 201 of the alpha-subunit of the signal transduction protein Gs (Gsalpha). The mutations have been found in many affected tissues of patients with MAS. Recently, a new missense mutation was detected in a patient with MAS, leading to the substitution of glycine for arginine at amino acid 201 of the Gsalpha gene, whereas no mutations have been reported at other sites in this gene. In the present study, we identified the activating mutations in the gene encoding Gsalpha protein in the osseous lesions of fibrous dysplasia and peripheral blood leukocyte in a 17-yr-old male patient with MAS. In addition, a heterozygous mutation encoding substitution of Arg201 of Gsalpha with His was found. Interestingly, we also found the other two types of mutations within the Gsalpha gene in the patient's affected osseous tissue. One is a combination mutation in the same allele at codons 209 and 210 of the Gsalpha gene, and the other the missense mutation at codon 235.

Endocrine manifestations of stimulatory G protein alpha-subunit mutations and the role of genomic imprinting

The heterotrimeric G protein G(s) couples hormone receptors (as well as other receptors) to the effector enzyme adenylyl cyclase and is therefore required for hormone-stimulated intracellular cAMP generation. Receptors activate G(s) by promoting exchange of GTP for GDP on the G(s) alpha-subunit (G(s)alpha) while an intrinsic GTPase activity of G(s)alpha that hydrolyzes bound GTP to GDP leads to deactivation. Mutations of specific G(s)alpha residues (Arg(201) or Gln(227)) that are critical for the GTPase reaction lead to constitutive activation of G(s)-coupled signaling pathways, and such somatic mutations are found in endocrine tumors, fibrous dysplasia of bone, and the McCune-Albright syndrome. Conversely, heterozygous loss-of-function mutations may lead to Albright hereditary osteodystrophy (AHO), a disease characterized by short stature, obesity, brachydactyly, sc ossifications, and mental deficits. Similar mutations are also associated with progressive osseous heteroplasia. Interestingly, paternal transmission of GNAS1 mutations leads to the AHO phenotype alone (pseudopseudohypoparathyroidism), while maternal transmission leads to AHO plus resistance to several hormones (e.g., PTH, TSH) that activate G(s) in their target tissues (pseudohypoparathyroidism type IA). Studies in G(s)alpha knockout mice demonstrate that G(s)alpha is imprinted in a tissue-specific manner, being expressed primarily from the maternal allele in some tissues (e.g., renal proximal tubule, the major site of renal PTH action), while being biallelically expressed in most other tissues. Disrupting mutations in the maternal allele lead to loss of G(s)alpha expression in proximal tubules and therefore loss of PTH action in the kidney, while mutations in the paternal allele have little effect on G(s)alpha expression or PTH action. G(s)alpha has recently been shown to be also imprinted in human pituitary glands. The G(s)alpha gene GNAS1 (as well as its murine ortholog Gnas) has at least four alternative promoters and first exons, leading to the production of alternative gene products including G(s)alpha, XLalphas (a novel G(s)alpha isoform that is expressed only from the paternal allele), and NESP55 (a chromogranin-like protein that is expressed only from the maternal allele). A fourth alternative promoter and first exon (exon 1A) located approximately 2.5 kb upstream of the G(s)alpha promoter is normally methylated on the maternal allele and transcriptionally active on the paternal allele. In patients with isolated renal resistance to PTH (pseudohypoparathyroidism type IB), the exon 1A promoter region has a paternal-specific imprinting pattern on both alleles (unmethylated, transcriptionally active), suggesting that this region is critical for the tissue-specific imprinting of G(s)alpha. The GNAS1 imprinting defect in pseudohypoparathyroidism type IB is predicted to decrease G(s)alpha expression in renal proximal tubules. Studies in G(s)alpha knockout mice also demonstrate that this gene is critical in the regulation of lipid and glucose metabolism.

Synthesis of a new class of 5'-functionalized adenosines using a rh(ii)-catalyzed 1,3-dipolar cycloaddition

[reaction: see text] Chemically protected adenosine was functionalized at the 5' position to generate novel dipolarophiles and mesoionic dipoles. These species were found to undergo facile 1,3-dipolar cycloaddition to afford a new series of adenosine derivatives that contain a point of diversification at the 5' position of adenosine.

"Café-au-lait spots" caused by vitiligo in McCune-Albright syndrome

Café-au-lait spots, fibrous dysplasia of bone, and endocrine gland hyperactivity are the principal features of McCune-Albright syndrome (MAS). Café-au-lait spots appear at, or soon after, birth. We illustrate "café-au-lait spots" acquired during middle age in a patient with MAS that are an illusion caused by vitiligo. This 64-year-old woman is the oldest patient reported with this disorder.